Set up a proportion, where x = the total number of students in 7th grade:
[tex]\frac{52}{x}=\frac{26}{100}[/tex]
Then, cross multiply and solve for x:
[tex]\frac{52}{x}=\frac{26}{100}\\26x=5200\\26x/26=5200/26\\x=200[/tex]
Therefore, there are 200 students in the 7th grade.